The undefeated boxer and the Irish UFC champion kicked off the four-city promotional tour for their Aug. 26 bout Tuesday, facing off in front of 11,000 fans in downtown Los Angeles.
McGregor and Mayweather traded clever insults and profane boasts with their familiar flair as they begin to sell a boxing match that could be much more entertaining before the opening bell.
McGregor was the crowd favorite as he made fun of Mayweather's IRS troubles and promised to flatten an aging fighter.
But Mayweather rose to the promotional challenge, leading his own fans in a call-and-response that derided the mixed martial artist as "easy work!"
Although the 40-year-old Mayweather acknowledged his skills have declined, he says he has "more than enough" to beat a rookie boxer.
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